title: Electrochemistry, surface plasmon resonance, and quartz crystal microbalance: an associative study on cytochrome c adsorption on pyridine tail-group monolayers on gold.
abstract: Quartz crystal microbalance (QCM), surface plasmon resonance (SPR), and electrochemistry techniques were used to study the electron-transfer (ET) reaction of cytochrome c (Cyt c) on gold surfaces modified with thionicotinamide, thioisonicotinamide, 4-mercaptopyridine, 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol, 5-phenyl-1,3,4-oxadiazole-2-thiol, 4,4'-bipyridine, and 4,4'-dithiopyridine. The electrochemical results showed that the ET process is complex, being chiefly diffusional with steps depending on the orientation of the pyridine or phenyl tail group of the modifiers. The correlation between the electrochemical results and those acquired by SPR and QCM indicated the presence of an adlayer of Cyt c adsorbed on the thiolate SAMs. This adlayer, although being not electroactive, is essential to assess the ET reaction of Cyt c in solution. The results presented in this work are consistent with the statement (Feng, Z. Q.; Imabayashi, S.; Kakiuchi, T.; Niki, K. J. Electroanal. Chem. 1995, 394, 149-154) that the ET reaction of Cyt c can be explained in terms of the through-bond tunneling mechanism.
authors.affiliation: Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Cx. Postal 6021, Fortaleza, Ceará, Brasil 60455-970.
authors.forename: Tércio de F
authors.initials: Tde F
authors.lastname: Paulo
authors.forename: Ticyano P
authors.initials: TP
authors.lastname: de Sousa
authors.forename: Dieric S
authors.initials: DS
authors.lastname: de Abreu
authors.forename: Nathalie H
authors.initials: NH
authors.lastname: Felício
authors.forename: Paul V
authors.initials: PV
authors.lastname: Bernhardt
authors.forename: Luiz G de F
authors.initials: LG
authors.lastname: Lopes
authors.forename: Eduardo H S
authors.initials: EH
authors.lastname: Sousa
authors.forename: Izaura C N
authors.initials: IC
authors.lastname: Diógenes
mesh_terms: D000327:Adsorption; D000818:Animals; D045304:Cytochromes c / Q000737:chemistry*; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D006736:Horses; D009206:Myocardium / Q000201:enzymology; D011725:Pyridines / Q000737:chemistry*; D058525:Quartz Crystal Microbalance Techniques; D020349:Surface Plasmon Resonance; D013499:Surface Properties
chemical_list: D011725:Pyridines; D006046:Gold; D045304:Cytochromes c